Method and apparatus for a hard disk drive including a balanced micro-actuator

ABSTRACT

This application discloses a hard disk drive, a head stack assembly, and a head gimbal assembly, each including a micro-actuator hinge configured to position a slider over a rotating disk surface with greater stroke sensitivity while reducing bending perpendicular to the disk surface. The micro-actuator hinge includes at least one micro-actuator, a hinge plate and at least one hinge plate cover, with the micro-actuator including a first region and a second region, each coupled between the hinge plate and the hinge plate cover.

TECHNICAL FIELD

This invention relates to hard disk drives using micro-actuators.

BACKGROUND OF THE INVENTION

Over the last several years, hard disk drives have reached ever greater data densities and with this, have needed ever better positioning mechanisms to access the data they stored on their disk surfaces. Existing positioning mechanisms tend to use piezoelectric micro-actuators that tend to pull or push the elements they couple to in directions perpendicular to the rotating disk surfaces being accessed. What is needed is a way to remove this extraneous motion and preferably increase motion in the plane of the disk surface that can be used to position the read-write elements over the data.

SUMMARY OF THE INVENTION

Embodiments of the invention include a hard disk drive with at least one head gimbal assembly using a micro-actuator hinge to position its slider over the rotating disk surface using at least one micro-actuator, including a first and second region coupling between a hinge plate and a hinge plate cover to effect each of the micro-actuators bending in essentially the plane of the rotating disk surface to at least partly alter the position of the slider over the disk surface. Simulation results indicate that some configurations may offer a 25% improvement in the stroke sensitivity of the micro-actuators while reducing bending perpendicular to the disk surface over prior art approaches. The micro-actuator may employ a thermal-mechanical effect and/or a preferred piezoelectric effect and/or a shape-memory. The micro-actuator hinge may preferably include at least two micro-actuators.

Other embodiments of the invention include the head gimbal assembly and the head stack assembly containing the micro-actuator hinge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an embodiment of the invention as a hard disk drive including a disk base to which a spindle motor is mounted with at least one disk rotatably coupled to the spindle motor to create a rotating disk surface. A voice coil motor includes a head stack assembly pivotably mounted by an actuator pivot to the disk base, responsive to its voice coil interacting with a fixed magnetic assembly mounted on the disk base and including a head gimbal assembly with a micro-actuator hinge configured to position at least one slider to access data stored on the rotating disk surface. The hard disk drive includes an assembled circuit board also mounted on the disk base opposite the spindle motor and the voice coil motor.

FIG. 2A shows a perspective view of the voice coil motor, its head stack assembly and the one or more head gimbal assemblies coupled to the one or more actuator arms of FIG. 1.

FIG. 2B shows a side view of some details of a head gimbal assembly of the previous Figures, in particular, the micro-actuator hinge coupling between the base plate and the load beam with a flexure finger coupled to the slider.

FIG. 3 shows a perspective view of some further details of the head gimbal assembly of the previous Figures with the micro-actuator hinge including a hinge plate with a first piezoelectric micro-actuator and a second piezoelectric micro-actuator each coupling a first region and a second region to the hinge plate and configured to alter the position of the slider as shown in FIGS. 1 and 2B. The piezoelectric micro-actuators have a preferred bending action essentially in the plane of the disk surface of previous Figures with minimal bending perpendicular to the disk surface.

FIG. 4 shows a cross section view of an example region of the piezoelectric micro-actuator of FIG. 3 coupling between the hinge plate and a hinge plate cover to minimize wasted motion out of the plane of the rotating disk of FIGS. 1 and 2B.

FIG. 5 shows a cross section view of an example region coupling to just the hinge plate as found in a prior art piezoelectric micro-actuator.

And FIG. 6 shows a simplified electrical schematic of the hard disk drive of FIG. 1 where the assembled circuit board includes a processor configured for electrical connection across the voice coil motor to the micro-actuator hinge to alter the position of the slider over the rotating disk surface. The processor is also configured to stimulate the voice coil motor to coarsely position the slider over the rotating disk surface. The processor further stimulates the spindle motor to rotate the disks of the hard disk drive to create the rotating disk surfaces.

DETAILED DESCRIPTION

This invention relates to hard disk drives using micro-actuators. Embodiments of the invention include a hard disk drive with at least one head gimbal assembly using a micro-actuator hinge to position its slider over the rotating disk surface using at least one micro-actuator, including a first and second region coupling between a hinge plate and a hinge plate cover to effect each of the micro-actuators bending in essentially the plane of the rotating disk surface to at least partly alter the position of the slider over the disk surface. Simulation results indicate that some configurations may offer a 25% improvement in the stroke sensitivity of the micro-actuators while reducing bending perpendicular to the disk surface over prior art approaches. The micro-actuator may employ a thermal-mechanical effect and/or a preferred piezoelectric effect and/or a shape-memory. The micro-actuator hinge may preferably include at least two micro-actuators.

Referring to the drawings more particularly by reference numbers, FIG. 1 shows an example of an embodiment of the invention as a hard disk drive 10 including a disk base 16 to which a spindle motor 14 is mounted with at least one disk 12 rotatably coupled to the spindle motor to create a rotating disk surface 6. A voice coil motor 46 includes a head stack assembly 50 pivotably mounted by an actuator pivot 42 to the disk base, responsive to its voice coil 42 interacting with a fixed magnetic assembly 44 mounted on the disk base and including a head gimbal assembly 28 with a micro-actuator hinge 26 configured to position at least one slider 20 to access data 15 stored on the rotating disk surface. The hard disk drive includes an assembled circuit board 60 also mounted on the disk base opposite the spindle motor and the voice coil motor. An assembled circuit board 60 is also mounted on the disk base opposite the spindle motor and the voice coil motor. A disk cover 18 is mounted on the disk base to encapsulate all of the shown components except the assembled circuit board.

The hard disk drive 10 preferably accesses the data 15 arranged in tracks on the rotating disk surface 6 by controlling the spindle motor 14 to rotate the disks 12 at a preferred rate. The data may be organized as tracks that may be configured as concentric circles or as a tightly packed spiral. The voice coil motor 46 operates by stimulating the voice coil 42 with a time varying electrical signal to magnetically interact with the fixed magnet assembly 34 causing the head stack assembly 50 to pivot about the actuator pivot 40 moving the head gimbal assembly 28 to position the slider 20 near the track on the rotating disk surface. In many embodiments, a micro-actuator assembly preferably coupled to the slider may be further stimulated to further control the position of the slider. A vertical micro-actuator either in the micro-actuator assembly, or preferably in the slider, may be stimulated to alter the flying height of the slider over the rotating disk surface.

FIG. 2A shows a perspective view of the voice coil motor 45, its head stack assembly 50 and the one or more head gimbal assemblies 28 coupled to the one or more actuator arms 48 of FIG. 1. The head stack assembly is configured to pivot about the actuator pivot 30.

FIG. 2B shows a side view of some details of a head gimbal assembly 28 of the previous Figures, in particular, the micro-actuator hinge 26 coupling between the base plate 24 and the load beam 22 with a flexure finger 27 coupled to the slider 20. The slider may use a perpendicular or longitudinal recording approach to accessing data on the rotating disk surface 6 and may employ a magneto-resistive effect or a tunneling effect to read the data. The slider may include a vertical micro-actuator or the flexure finger may include a vertical micro-actuator. Either approach to vertical micro-actuation may employ a thermal-mechanical effect, a piezoelectric effect, and/or an electro-static effect.

FIG. 3 shows a perspective view of some further details of the head gimbal assembly 28 of the previous Figures with the micro-actuator hinge 26 including a hinge plate 30 shown in dashed lines with a first piezoelectric micro-actuator 32 and a second piezoelectric micro-actuator 34 each coupling a first region 100 and a second region 102 to the hinge plate and configured to alter the position of the slider 20 as discussed with regards to FIGS. 1 and 2B. The hinge plate cover 36 is not shown in this Figure. The piezoelectric micro-actuators have a preferred bending action essentially in the plane of the disk surface 6 of previous Figures with minimal bending perpendicular to the disk surface. In this Figure, the coupling of the piezoelectric micro-actuators favors the same regions coupled toward the base plate 24. In other embodiments, the opposite coupling of regions may be preferred. The flexure finger 27 is shown further providing coupling to the load beam 22 and to the slider 20 as shown in FIG. 2B.

FIG. 4 shows a cross section view of an example region 100 of FIG. 3 coupling between the hinge plate 30 and a hinge plate cover 36. The hinge plate is coupled to both the top 106 and bottom 104 of each region 100 and 102 of the piezoelectric micro-actuators 32 and 34, reducing bending of these micro-actuators perpendicular to the rotating disk surface 6. Each of these piezoelectric micro-actuators preferably extends or compresses essentially in the plane of the rotating disk surface. Simulation results indicate that some configurations may offer a 25% improvement in the stroke sensitivity of the micro-actuators while reducing bending perpendicular to the disk surface over prior art approaches as shown in FIG. 5.

For at least one of the piezoelectric micro-actuators 32 and/or 34, the micro-actuator may have at least ten percent of its area covered by the first region 100 and/or second region 102.

The second region 102 may be between the hinge plate 30 and a second hinge plate cover 36 for at least one of the piezoelectric micro-actuators 32 and/or 34.

The hinge plate cover 36 may be between the hinge plate 30 and the rotating disk surface 6. Alternatively, the hinge plate may be between the hinge plate cover and the rotating disk.

By way of comparison, FIG. 5 shows a cross section view of an example region 100 coupling to just the hinge plate 30 as found in the prior art.

FIG. 6 shows a simplified electrical schematic of the hard disk drive 10 of FIG. 1 where the assembled circuit board 60 includes a processor 62 configured for electrical connection 64 across the voice coil motor 46 to the micro-actuator hinge 26 to alter the position of the slider 20 over the rotating disk surface 6. The processor is also configured to stimulate 66 the voice coil motor to coarsely position the slider over the rotating disk surface. The processor further stimulates 68 the spindle motor 14 to rotate the disks 12 of the hard disk drive to create the rotating disk surfaces.

When the hard disk drive 10 has been turned on and data is to be accessed in the hard disk drive, the processor 62 stimulated the spindle motor 14 to rotate the disks 12 to create the rotating disk surface 6. The processor stimulates the voice coil 42 in the voice coil motor 46 with a time-varying electrical signal, causing the voice coil to magnetically interact with the fixed magnetic assembly 44 of FIGS. 1 and 2A moving the actuator arms 48 through the actuator pivot 42 to swing the head gimbal assemblies 28, to coarsely position their sliders 20 of the data 15 on the rotating disk surface.

Once the slider 20 is in position, when a write operation is to be performed the data 15 is written through the slider onto the rotating disk surface 6. When a read operation is to be performed, the slider is used to read the data from the rotating disk surface into the processor 62. Often a Position Error Signal (PES) is derived from the read head of the slider to provide feedback to the processor 62 on the positioning of the slider over the rotating disk surface 6.

Based upon the PES, the processor electrically may stimulate 64 the micro-actuator hinge 26 in the head gimbal assembly to further alter the position of the slider over the rotating disk surface as shown in FIGS. 5A and 5B.

Several different electrical schemes may be used to implement the electrical connection 64 across the voice coil motor 46. For example, a single control signal capable of a range between the first potential difference above a ground to the negative of the first potential difference may be employed. The delivery of the single control signal and a ground may be preferred in some embodiments of the invention, though other scheme involving more active signal lines may also be preferred.

The preceding embodiments provide examples of the invention, and are not meant to constrain the scope of the following claims. 

1. A hard disk drive, comprising: a disk base; a spindle motor mounted on said disk base and rotatably coupled to at least one disk to create at least one rotating disk surface; a voice coil motor pivotably mounted to said disk base to position via a head gimbal assembly at least one slider over said rotating disk surface, said head gimbal assembly including a micro-actuator hinge coupling between a base plate and a load beam with a flexure finger coupled to said slider, said micro-actuator hinge comprising a hinge plate, at least one hinge plate cover and at least one micro-actuator including a first region and a second region, both of said regions coupled between said hinge plate and said hinge plate cover to effect said micro-actuator bending in essentially the plane of said rotating disk surface to at least partly alter said position of said slider over said rotating disk surface.
 2. The hard disk drive of claim 1, wherein for at least one of said micro-actuators, said first region is covered between said hinge plate and said hinge plate cover constitutes at least ten percent of the area of said micro-actuator.
 3. The hard disk drive of claim 1, wherein for at least one of said micro-actuators, said second region is between said hinge plate and a second of said hinge plate covers.
 4. The hard disk drive of claim 1, wherein for each of said micro-actuators, said second region is between said hinge plate and said hinge plate cover.
 5. The hard disk drive of claim 1, wherein said hinge plate cover is between said hinge plate and said rotating disk surface.
 6. The hard disk drive of claim 1, wherein said micro-actuator employs at least one member of the group consisting of a thermal-mechanical effect, a piezoelectric effect and a shape memory alloy.
 7. The hard disk drive of claim 1, wherein said micro-actuator hinge further comprises at least two of said micro-actuators.
 8. A head stack assembly configured for use in a hard disk drive, comprising: an actuator pivot for pivotably mounting to a disk base; at least one actuator arm rigidly coupled to said actuator pivot; at least one head gimbal assembly rigidly coupled to said actuator arm and configured to position at least one slider over a rotating disk surface in said hard disk drive, said head gimbal assembly including a micro-actuator hinge coupling between a base plate and a load beam with a flexure finger coupled to said slider, said micro-actuator hinge comprising a hinge plate, at least one hinge plate cover and at last one micro-actuator including a first region and a second region, both of said regions coupled between said hinge plate and said hinge plate cover to effect said micro-actuator bending in essentially the plane of said rotating disk surface to at least partly alter said position of said slider over said rotating disk surface.
 9. The head stack assembly of claim 8, wherein for at least one of said micro-actuators, said first region is covered between said hinge plate and said hinge plate cover constitutes at least ten percent of the area of said piezoelectric micro-actuator.
 10. The head stack assembly of claim 8, wherein for at least one of said micro-actuators, said second region is between said hinge plate and a second of said hinge plate covers.
 11. The head stack assembly of claim 8, wherein for each of said micro-actuators, said second region is between said hinge plate and said hinge plate cover.
 12. The head stack assembly of claim 8, wherein said hinge plate cover is between said hinge plate and said rotating disk surface.
 13. The head stack assembly of claim 8, wherein said micro-actuator employs at least one member of the group consisting of a thermal-mechanical effect, a piezoelectric effect and a shape memory alloy.
 14. The head stack assembly of claim 8, wherein said micro-actuator hinge further comprises at least two of said micro-actuators.
 15. A head gimbal assembly configured to position at least one slider over a rotating disk surface in said hard disk drive, comprising: a micro-actuator hinge coupling between a base plate and a load beam with a flexure finger coupled to said slider, said micro-actuator hinge comprising a hinge plate, at least one hinge plate cover, at least one micro-actuator including a first region and a second region, both of said regions coupled between said hinge plate and said hinge plate cover to effect said micro-actuator bending in essentially the plane of said rotating disk surface to at least partly alter said position of said slider over said rotating disk surface.
 16. The head gimbal assembly of claim 15, wherein for at least one of said micro-actuators, said first region is covered between said hinge plate and said hinge plate cover constitutes at least ten percent of the area of said piezoelectric micro-actuator.
 17. The head gimbal assembly of claim 15, wherein for at least one of said micro-actuators, said second region is between said hinge plate and a second of said hinge plate covers.
 18. The head gimbal assembly of claim 15, wherein for each of said micro-actuators, said second region is between said hinge plate and said hinge plate cover.
 19. The head gimbal assembly of claim 15, wherein said hinge plate cover is between said hinge plate and said rotating disk surface.
 20. The head gimbal assembly of claim 15, wherein said micro-actuator employs at least one member of the group consisting of a thermal-mechanical effect, a piezoelectric effect and a shape memory alloy.
 21. The head gimbal assembly of claim 15, wherein said micro-actuator hinge further comprises at least two of said micro-actuators. 